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Number of own siblings in household


0 = N.I.U. (Not in Universe; Zero siblings).
9 = 9 or more siblings (Topcode).


NSIBS counts the number of own siblings (including half-siblings, step-siblings, and adopted siblings) residing with each individual. Persons with no siblings present are coded 0.

Note that NSIBS is an IPUMS-derived variable using IPUMS-derived family interrelationships. Thus NSIBS may differ from any family information that comes from just the Census family definitions. See for example FTYPE, FAMKIND, and FAMREL for more on Census family units.


The comparability of this variable is affected by the information available on family relationships. NSIBS is based on the information contained in RELATE (Relationship to household head), MOMLOC, MOMLOC2, POPLOC, and POPLOC2. See MOMLOC, MOMLOC2, POPLOC, and POPLOC2 for discussion of variations across years in these variables.

Comparability with IPUMS-USA

The development of new family interrelationship variables was prompted by the desire to have more comparability between different IPUMS projects and over time. The family interrelationship variables use common logic across IPUMS CPS, IHIS, and USA (modern years). Each project has different allowed links because of different level of detail in each project, but the logic of assigning parents in ambiguous situations is the same.


  • All persons.


Years Jan Feb ASEC Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1968 – 1975 - - X - - - - - - - - - -
1976 – 2023 X X X X X X X X X X X X X
2024 X X - X X X - - - - - - -


This variable has no flags.

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